/*
 * Copyright (c) 2003 The Visigoth Software Society. All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution, if
 *    any, must include the following acknowledgement:
 *       "This product includes software developed by the
 *        Visigoth Software Society (http://www.visigoths.org/)."
 *    Alternately, this acknowledgement may appear in the software itself,
 *    if and wherever such third-party acknowledgements normally appear.
 *
 * 4. Neither the name "FreeMarker", "Visigoth", nor any of the names of the 
 *    project contributors may be used to endorse or promote products derived
 *    from this software without prior written permission. For written
 *    permission, please contact visigoths@visigoths.org.
 *
 * 5. Products derived from this software may not be called "FreeMarker" or "Visigoth"
 *    nor may "FreeMarker" or "Visigoth" appear in their names
 *    without prior written permission of the Visigoth Software Society.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE VISIGOTH SOFTWARE SOCIETY OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Visigoth Software Society. For more
 * information on the Visigoth Software Society, please see
 * http://www.visigoths.org/
 */

package org.kurento.modulecreator.codegen;

import java.io.File;
import java.io.IOException;
import java.io.Reader;
import java.nio.charset.Charset;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.attribute.BasicFileAttributeView;
import java.nio.file.attribute.BasicFileAttributes;

import freemarker.cache.TemplateLoader;

/**
 * A {@link TemplateLoader} that uses Paths in a specified directory as the source of templates.
 */
public class PathTemplateLoader implements TemplateLoader {

  private static final boolean SEP_IS_SLASH = File.separatorChar == '/';

  public final Path baseDir;

  /**
   * Creates a new file template loader that will use the specified directory as the base directory
   * for loading templates.
   * 
   * @param baseDir
   *          the base directory for loading templates
   */
  public PathTemplateLoader(final Path baseDir) throws IOException {
    this.baseDir = baseDir;
  }

  @Override
  public Object findTemplateSource(final String name) throws IOException {

    String processedName = SEP_IS_SLASH ? name : name.replace('/', File.separatorChar);
    Path source = baseDir.resolve(processedName);

    if (!Files.exists(source) || Files.isDirectory(source)) {
      return null;
    }

    return source;
  }

  @Override
  public long getLastModified(final Object templateSource) {

    Path templateAsPath = (Path) templateSource;
    BasicFileAttributeView basicView = Files.getFileAttributeView(templateAsPath,
        BasicFileAttributeView.class);

    // This attribute view is perhaps not available in this system
    if (basicView != null) {

      BasicFileAttributes basic;
      try {
        basic = basicView.readAttributes();
      } catch (IOException e) {
        return -1;
      }

      return basic.lastModifiedTime().toMillis();

    } else {
      return -1;
    }
  }

  @Override
  public Reader getReader(final Object templateSource, final String encoding) throws IOException {

    if (!(templateSource instanceof Path)) {
      throw new IllegalArgumentException(
          "templateSource is a: " + templateSource.getClass().getName());
    }

    return Files.newBufferedReader((Path) templateSource, Charset.forName(encoding));
  }

  @Override
  public void closeTemplateSource(Object templateSource) {
    // Do nothing.
  }
}